Exchange Surfaces & Exchange Substances

Cards (13)

  • Specialized exchange surfaces
    Parts of an organism over which they exchange substances with their environment
  • Specialized exchange surfaces in humans
    • Alveoli
    • Villi
  • Alveoli
    • Small sac-like things found in the lungs at the very ends of the bronchioles
    • Exchange oxygen and carbon dioxide between the air and the blood
  • Villi
    • Finger-like things found on the inside lining of the small intestines
    • Help absorb nutrients like glucose and amino acids
  • Specialized exchange surfaces in plants
    • Root hair cells
    • Leaves
  • Root hair cells
    • Help absorb water and mineral ions from the soil
  • Leaves
    • Help absorb the carbon dioxide they need from the air
  • Common features of specialized exchange surfaces
    • Large surface area
    • Thin surfaces
    • Permeable to substances they need to exchange
    • Good blood supply (internal medium)
    • Good supply of external medium
  • Large surface area
    Allows more molecules to diffuse across at the same time, increasing the rate of diffusion
  • Thin surfaces
    Short diffusion path, allowing faster diffusion
  • Permeable
    Allows substances to diffuse across rather than blocking them
  • Good blood supply

    Helps maintain a concentration gradient for substances to diffuse into the blood
  • Good supply of external medium
    Helps maintain a concentration gradient for substances to diffuse into the organism, e.g. air for alveoli, food for villi